Bev. Dr. Irving— On Dynamic Mefamorphism. 299 



It is stated that, " Wbether it be atomic energy or not, is not at 

 present known." Does this mean that we cannot distinguish between 

 the energy of translation of the molecules of a gas or the energy of 

 cohesion of the molecules of a solid, and the intra-molecular energy 

 which the atoms possess per se ? Is it meant to say that recent 

 advances in chemical physics have not led to the recognition of the 

 atom-temperature within the molecule as affecting for the time being 

 the stability of the molecule itself? Does it mean to tell us that 

 we cannot, in the light of a host of known facts, draw a distinction 

 between those molecular moods or states of matter which we call 

 magnetic and electric, and that interaction between the atoms which 

 is concerned in building up those molecules, and which we call 

 chemical affinity ? Or, turning to his own chosen examples, can 

 Mr. Fisher's authority bring forward any array of cogent facts to 

 shake or overthrow the doctrine that the avidity with which CO 

 takes up oxygen (whether free or combined) when the temperature 

 is raised, and that most characteristic avidity with which NO takes 

 up O2 (at ordinary temperatures) is in both cases due, not to any force 

 resident in the molecule as such, but to the unsaturated valency of 

 the C-atom or the N-atom respectively ? Intra-molecular energy 

 seems to me as clearly distinguishable from molecular energy, as the 

 latter is from " ordinary mechanical or molar energy." ^ 



Beverting now to Mr. Fisher's original paper in the Geological 

 Magazine (July, 1890), I think I can follow his reasoning pretty 

 clearly, until on p. 304 he says: "We must now inquire into 

 what forms of energy the work has been converted." Here there 

 seems to me some confusion of thought. ' Energy ' is the capacity 

 for doing work ; that is, for producing or retarding motion, or over- 

 coming resistance to motion. The amount of energy expended is 

 always proportionate to the work done. In the case before us the 

 energy is presented in the mechanical form of pressure, and if the 

 lateral pressure is the result of the original * energy of position ' of 

 another portion of the Earth's crust, the actual source of the energy 

 is gravitation acting upon the mass favourably situated. This being 

 in part resolved into lateral thrust, the energy of that thrust is 

 expended in doing work which is distributed among the following 

 terms : ^ — 



1. The lifting of the cover (potential energy of position) ; 



2. The elevation of the centre of gravity of the deformed mass, 

 in so far as the extension of the mass takes place upwards (potential 

 energy of position) ; 



3. The work of compression (molecular friction generating heat) ; 



4. The work of shearing, bending, and fracture. 



Where I am unable to follow Mr. Fisher's reasoning is with 

 reference to the last term, which is surely outside the others altogether. 



^ Since writing this paper I have noticed that the above cases with some others 

 are discussed in a very suggestive (though scarcely exhaustive) manner by Professor 

 Liveing in his little book " Chemical Equilibrium, the Eesult of Dissipation of 

 Energy" (1885). 



^ Eef erring to the geometrical construction used by Mr. Fisher {loc. cit.) . 



